\(\displaystyle-\frac{{1}}{{3}}{t}\le-{5}\)

\(\displaystyle-\frac{{1}}{{3}}{t}\times{\left(-{3}\right)}\le-{5}\times{\left(-{3}\right)}\)

\(\displaystyle{t}\ge{15}\), which means that inequalities are equivalent.

\(\displaystyle-\frac{{1}}{{3}}{t}\times{\left(-{3}\right)}\le-{5}\times{\left(-{3}\right)}\)

\(\displaystyle{t}\ge{15}\), which means that inequalities are equivalent.